"You still don't understand what you're dealing with, do you? The perfect organism. Its structural perfection is matched only by its hostility. I admire its purity. A survivor … unclouded by conscience, remorse, or delusions of morality." - Ash to Ripley (Alien, 1979)

Sunday, April 17, 2011

Yellow Watchman Goby and Tiger Pistol Shrimp: Best Friends for Life

Many species on this earth have evolved to create very unique relationships with each other. One of the most unique relationships is that of the shrimp and goby. These creatures have a mutualistic relationship with each other and is it suggested that without one another, they would not live very long. Together, they live in a burrowed out home usually found on the sandy ocean floor. While the shrimp digs out the home, the goby stays watches out for the blind shrimp like a watchdog. Through the cooperation of both, these creatures thrive in the scary world of the ocean.

The goby fish are from the family Gobiidae. This family of fish contains 2,200 species of fish. [2] . Many of these gobies are known to have the mutualistic relationship with the shrimp.A perfect example of this relationship is the relationship of the yellow watchman goby, or the Cyrptocentrus cinctus, and the tiger pistol shrimp, or the Alpheus bellulus. The yellow watchman goby is a yellow colored goby and the tiger pistol shrimp is a tanned bodied shrimp that is characterized with rust colored broken stripes running across their backs. [3][4]

These creatures can be found in sand flats on coral reefs and shallow lagoons and can reach a depth of 3-50 ft. Often, their homes are found under rocks or coral reef rubble. Typically, these creatures can be seen inhabiting shallow sea floors in parts of the Pacific Ocean and the Red Sea. [6]

The yellow watchman goby reproduces sexually; they undergo usual fish-sexual means of reproduction (fertilizing eggs, laying eggs, eggs hatching, and young growing into adults). The lifespan of this species of fish is usually 5 years. [7] The adult gobies are known for making this mutualistic relationship with the shrimp.

The tiger pistol shrimp reproduce sexually. From the laid eggs, they develop into adults. As with the gobies, the adults are the ones known to make this unusual relationship. The typical lifespan of this shrimp is from 5-8 years. [8]

The Relationship:

One of the reastons as to why the yellow watchman goby and the tiger pistol shrimp have evolved this interesting relationship, is because this particular species of goby are horrible burrowers and the tiger pistol shrimp are blind. Both of these traits, without help, can lead these organisms to being an easy prey. When combined together, they almost complete one another: This goby in opposite to the shrimp can see and the shrimp are wonderful burrowers. It is because of these traits that these two creatures have adapted to living together.

Looking at the relationship, the shrimp burrows out a home for the goby, while the goby watches and looks out for the shrimp and itself. During the day, the goby keeps watch outside of the home and will protect the shrimp if it wonders out for a meal. At night, both the shrimp and the goby sleep together peacefully in the house. [9] Occasionally, 2 gobies will live in the same home with the shrimp.

The way the goby protects the shrimp is through the shrimp's and the goby’s communication. When the shrimp emerges from the burrowed home, they do not wonder far. They try to stay around the hole leading down to their home. The shrimp uses their antennas to make sure they do not stray far from the goby. The shrimp keeps their antenna in contact with the goby’s tail and can feel the goby and they know whether or not they go too far. The goby keeps watch for both of them. If the goby senses danger, it will flicker its tail. The shrimp will receive the alert and will either retreat back into the home or stay still. If danger is bad enough, the goby will dive head first into the burrow, but when this happens, the goby always follows the shrimp in. If the shrimp strays too far from the home, the goby will stay with it and will lead the blind shrimp back. [3][11]

One of main questions is as to how these organisms go about finding each other? It has been suggested that the goby is attracted to the sight of the blind shrimp while the shrimp is chemically attracted to the goby. This means if the shrimp senses any chemicals that are related to the said goby, they will make their way to them. With the goby, if the goby sees a blind shrimp or their burrow, they will swim their way to them. Either way, they will find each other and will set up their mutualistic relationship. [13]

Benefits:

The benefits of the shrimp are that they receive protection from any harm and will be granted a guide through the scary seawaters. The benefits of the goby are that they have a home and will not have to worry about the home falling in because of the shrimp’s constant maintenance of the home. In this, they receive shelter. Also, the tiger pistol shrimp is known to share its food with the goby. [14]

Costs:

The costs of the shrimp are that they cannot live without the guidance/protection of the goby. Because they are blind, they are completely reliant on the goby’s guiding and their protection. The goby in return cannot burrow a hole properly. Without the shrimp, they would have to find alternative methods of a home. In most places in the ocean world, an empty hole would be hard to find. The goby is almost completely reliant on the shrimp for finding a home.

3 comments:

Both organisms in this relationship seem evolutionarily disadvantaged. If one of the species were to become extinct, do you think that the surviving species would adapt, like finding another partner to form a mutualistic relationship? Or, like the Red Queen Hypothesis states, would they be able to adapt and evolve traits in order to maintain defenses against natural prey?

Sarika: The only thing I found in my research was what I mentioned in the blog: the goby protects the shrimp, the shrimp maintains the home, and the shrimp shares its food with the goby.

Morgan: Yes, I do believe that given the right circumstances, I do believe that these species will have the potential to find another mutualistic partner and to adapt their defenses against predators. Out of the relationship, I think that because the shrimp is blind, it will be one most likely to undergo the most adaptations. The one thing that will define whether or not it finds another partner or maintain their defenses will be the likeliness the species will find another partner. If it doesn't, it will have to heighten its defenses.